/Engine/Source/Editor/UnrealEd/Public/Toolkits/AssetEditorToolkit.h
For standalone asset editing tool-kits, returns the toolkit host that was last hosting this asset editor before it was switched to standalone mode (if it's still valid.) Returns null if these conditions aren't met.
[TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [IToolkitHost](API\Editor\EditorFramework\Toolkits\IToolkitHost) > GetPreviousWorldCentricToolkitHost()